U.S. Border Patrol agents in Texas detain undocumented immigrants after they crossed the border from Mexico in August. (John Moore/Getty Images)

Consider the paddy wagon. From the mid-19th century through the mid-20th, this was the common term for the vehicles in which police hauled convicts and arrestees to jails, courts and prisons. Consider, now, the origin of the term. The “paddies” were Irish immigrants, who were flocking to the United States in the 1840s and ’50s, fleeing the great famine that had descended on Ireland. And the Irish, some right-thinking Protestant Americans believed, were inherently a criminal bunch.

In the 1840s and ’50s, there were enough of those right-thinking Americans to form a political party: the American Party, they called it, though (because when asked about their doings, many apparently paranoid members responded, “I know nothing”) it soon came to be known as the Know Nothings. With Irish and German immigrants flooding into the country (the Germans largely fleeing the repression that followed the failed revolutions of 1848), the Know Nothings experienced a brief surge of popularity until the far greater conflict between slave states and free states led to a more fundamental reshuffling of political parties. Some Know Nothings drifted into the ranks of the newly formed Republican Party. One early GOP leader, Abraham Lincoln, did everything he could to squelch their influence and make clear that German, Irish and all other immigrants were welcome additions to the party and the nation.

Like most immigrant groups, the Irish took the hardest, most thankless jobs — building railroads, for instance. Nonetheless, the nativist leaders of the time — the 1850s version of Fox News chief Roger Ailes — insisted that guys with names like Hannity and O’Reilly were inherently disposed to crime and violence, undeterred by the absence of data that backed up their claims.

’Twas ever thus. Italians were criminals or anarchists; Jews were criminals (as in “The Great Gatsby”) or communists; Mexicans, if you believe Donald Trump, are rapists and murderers. Never mind, as a recent voluminous study by the National Academy of Sciences makes clear, that the linkage between immigrants and crime is not merely fictitious but actually inverse: After close statistical analysis, the study concludes, “Immigrants are in fact much less likely to commit crime than natives, and the presence of large numbers of immigrants seems to lower crime rates.” Based on the findings of at least 30 academic papers, the study concludes that foreign-born young men have an incarceration rate that is one-fourth that of native-born, and that “neighborhoods with greater concentrations of immigrants have lower rates of crime and violence” than other socioeconomically equivalent neighborhoods.

Indeed, the growing number of the foreign-born over the past quarter-century goes a long way to explaining the huge drop in crime and violence that the nation has experienced during that time. The number of murders in New York City dropped from 2,245 in 1990 to 328 last year; in Los Angeles County it fell from 1,944 in 1993 to 551 last year, even as the number and share of their foreign-born residents skyrocketed. Nationally, in 2014 violent crime rates were at their lowest level in 20 years, according to the FBI.

The immigrant crime wave that right-wing media and many Republican politicians rail about, then, is either a figment of their imaginations or an article of faith that, whatever their individual beliefs, they seek to instill or inflame in their followers. These beliefs are as valid as their predecessors’ claims that the Irish or the Chinese, say, posed a danger to the United States and that no more of them should be allowed in. They are in the grand tradition of Madison Grant’s hugely influential 1916 book “The Passing of the Great Race,” which argued that the “Nordics” of Northwestern Europe were a superior race to Southern and Eastern Europeans (Italians, Jews, Greeks et al.), and that immigration from anyplace other than Northwest Europe should be banned. In 1924, Congress did just that, enacting a law that effectively restricted immigration from all but the “Nordic” nations, a law that stayed on the books until the Great Society Congress of 1965 repealed it.

So to those who want to repeal birthright citizenship and send those dangerous Mexicans back to their homeland: Why stop there? Donald Trump’s claims about the dangers posed by Mexicans are no more valid than Madison Grant’s about the Italian and Jewish menace, or the Know Nothings’ about the criminal tendencies of the Irish. Deporting the Gonzalezes makes sense only if we also deport the O’Reillys and the Hannitys and, yes, the Meyersons. See you all, ladies and gentlemen, on some distant shore.

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